Incahuasi (; possibly from Quechua: inka Inca, wasi house) is a volcanic mountain in the Andes of South America. It lies on the border of the Catamarca Province of Argentina and the Atacama Region of Chile. Incahuasi has a summit elevation of above sea level. The volcano consists of a caldera and two stratovolcanoes. Four pyroclastic cones located to the northeast have produced basalt-andesite lava flows that cover an area of . Geography and geology Incahuasi lies on the border between Argentina and Chile, close to Paso San Francisco. A major road crosses the border there. Regional Incahuasi is part of the Central Volcanic Zone of the Andes, together with about 110 other Quaternary volcanoes, and lies in the southern sector of this zone; other volcanic zones in the Andes are the Northern Volcanic Zone, the Southern Volcanic Zone, and the Austral Volcanic Zone. The history of volcanic activity of most of these volcanoes is poorly understood owing to the lack of dating; only a few historical eruptions have been recorded, such as an eruption at Ojos del Salado in 1993. Incahuasi is located northeast of Ojos del Salado, the highest volcano in the world. Both volcanoes are found at the southern end of the Central Volcanic Zone. Together with El Fraile, Cerro El Muerto, Nevado Tres Cruces, and El Solo, they form a volcanic chain. The area is dominated by volcanoes that were active after 1.5 million years ago. Also located close to Incahuasi are Falso Azufre and Nevado San Francisco, as well as the Miocene Cerro Morocho and Cerro Ojo de Las Lozas volcanoes. It has been suggested that a perpendicular chain of volcanoes including Ojos del Salado may be the consequence of the Juan Fernández Ridge subducting in the Peru–Chile Trench. Geological evidence suggests that volcanism in the area dates back to the Oligocene and Miocene, when the main volcanic arc was located west in the Maricunga Belt. Between 9 and 6 million years ago, volcanic activity in the Maricunga Belt decreased and eventually ceased. Simultaneously, the back-arc experienced increased volcanic activity. Beginning 8.3 million years ago, there was a change in tectonic regime from an east-west compression to a north-south stretching, which led to a change in the alignments of the volcanoes. Local Incahuasi is formed by a caldera wide. Two coalesced stratovolcanoes formed within the caldera and have a diameter of . A lava dome